Email attacks have moved past standard phishing and become more targeted over the years. In this article, I will focus on email impersonation attacks, outline why they are dangerous, and provide some tips to help individuals and organizations reduce their risk exposure to impersonation attacks.
What are email impersonation attacks?
Email impersonation attacks are malicious emails where scammers pretend to be a trusted entity to steal money and sensitive information from victims. The trusted entity being impersonated could be anyone – your boss, your colleague, a vendor, or a consumer brand you get automated emails from.
Email impersonation attacks are tough to catch and worryingly effective because we tend to take quick action on emails from known entities. Scammers use impersonation in concert with other techniques to defraud organizations and steal account credentials, sometimes without victims realizing their fate for days after the fraud.
Fortunately, we can all follow some security hygiene best practices to reduce the risk of email impersonation attacks.
Tip #1 – Look out for social engineering cues
Email impersonation attacks are often crafted with language that induces a sense of urgency or fear in victims, coercing them into taking the action the email wants them to take. Not every email that makes us feel these emotions will be an impersonation attack, of course, but it’s an important factor to keep an eye out for, nonetheless.
Here are some common phrases and situations you should look out for in impersonation emails:
- Short deadlines given at short notice for processes involving the transfer of money or sensitive information.
- Unusual purchase requests (e.g., iTunes gift cards).
- Employees requesting sudden changes to direct deposit information.
- Vendor sharing new.
This email impersonation attack exploits the COVID-19 pandemic to make an urgent request for gift card purchases.
Tip #2 – Always do a context check on emails
Targeted email attacks bank on victims being too busy and “doing before thinking” instead of stopping and engaging with the email rationally. While it may take a few extra seconds, always ask yourself if the email you’re reading – and what the email is asking for – make sense.
- Why would your CEO really ask you to purchase iTunes gift cards at two hours’ notice? Have they done it before?
- Why would Netflix emails come to your business email address?
- Why would the IRS ask for your SSN and other sensitive personal information over email?
To sum up this tip, I’d say: be a little paranoid while reading emails, even if they’re from trusted entities.
Tip #3 – Check for email address and sender name deviations
To stop email impersonation, many organizations have deployed keyword-based protection that catches emails where the email addresses or sender names match those of key executives (or other related keywords). To get past these security controls, impersonation attacks use email addresses and sender names with slight deviations from those of the entity the attacks are impersonating. Some common deviations to look out for are:
- Changes to the spelling, especially ones that are missed at first glance (e.g., “ei” instead of “ie” in a name).
- Changes based on visual similarities to trick victims (e.g. replacing “rn” with “m” because they look alike).
- Business emails sent from personal accounts like Gmail or Yahoo without advance notice. It’s advisable to validate the identity of the sender through secondary channels (text, Slack, or phone call) if they’re emailing you with requests from their personal account for the first time.
- Descriptive changes to the name, even if the changes fit in context. For example, attackers impersonating a Chief Technology Officer named Ryan Fraser may send emails with the sender name as “Ryan Fraser, Chief Technology Officer”.
- Changes to the components of the sender name (e.g., adding or removing a middle initial, abbreviating Mary Jane to MJ).
Tip #4 – Learn the “greatest hits” of impersonation phrases
Email impersonation has been around for long enough that there are well-known phrases and tactics we need to be aware of. The emails don’t always have to be directly related to money or data – the first email is sometimes a simple request, just to see who bites and buys into the email’s faux legitimacy. Be aware of the following phrases/context:
- “Are you free now?”, “Are you at your desk?” and related questions are frequent opening lines in impersonation emails. Because they seem like harmless emails with simple requests, they get past email security controls and lay the bait.
- “I need an urgent favor”, “Can you do something for me within the next 15 minutes?”, and other phrases implying the email is of a time-sensitive nature. If you get this email from your “CEO”, your instinct might be to respond quickly and be duped by the impersonation in the process.
- “Can you share your personal cell phone number?”, “I need your personal email”, and other out-of-context requests for personal information. The objective of these requests is to harvest information and build out a profile of the victim; once adversaries have enough information, they have another entity to impersonate.
Tip #5 – Use secondary channels of authentication
Enterprise adoption of two-factor authentication (2FA) has grown considerably over the years, helping safeguard employee accounts and reduce the impact of account compromise.
Individuals should try to replicate this best practice for any email that makes unusual requests related to money or data. For example:
- Has a vendor emailed you with a sudden change in their bank account details, right when an invoice is due? Call or text the vendor and confirm that they sent the email.
- Did your manager email you asking for gift card purchases? Send them a Slack message (or whatever productivity app you use) to confirm the request.
- Did your HR representative email you a COVID resource document that needs email account credentials to be viewed? Check the veracity of the email with the HR rep.
Even if you’re reaching out to very busy people for this additional authentication, they will understand and appreciate your caution.
These tips are meant as starting points for individuals and organizations to better understand email impersonation and start addressing its risk factors. But effective protection against email impersonation can’t be down to eye tests alone. Enterprise security teams should conduct a thorough audit of their email security stack and explore augments to native email security that offer specific protection against impersonation.
With email more important to our digital lives than ever, it’s vital that we are able to believe people are who their email says they are. Email impersonation attacks exploit this sometimes-misplaced belief. Stopping email impersonation attacks will require a combination of security hygiene, email security solutions that provide specific impersonation protection, and some healthy paranoia while reading emails – even if they seem to be from people you trust.